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yaorong · 3 years

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What are PAR and PPFD in LED plant lights, and why are they rating indicators?

PAR (Photosynthetically Active Radiation) describes the part of the visible spectrum (400nm-700nm) that plants "see" and use for photosynthesis. PPFD (photosynthetic photon flux density) measures the amount of light (PAR) that plants receive over time. PPFD represents the light density received by plants over time, measured in units of micromoles per square meter per second.

PAR (photosynthetically active radiation)

PAR is simply understood as the light suitable for plant growth. Traditional industrial and commercial applications of LED lighting are designed to illuminate the work space for human activities. This means that the only important spectrum is the very narrow central curve perceived by the human eye, and we measure it in lumens. The number of available lumens in a given area is an accurate measurement of the light output and coverage of these applications. The relationship between plants and light is very different, so the way we measure light in gardening is very different.

All plants draw nutrients and growth cues from natural sunlight, and respond to a wider range of lighting chromatograms that humans usually perceive. The spectrum that affects plant growth is in the 400 to 700 nanometer range, involving more red and blue at the end of the spectrum. Because of its positive role in photosynthesis, we call this light photosynthetically active radiation (PAR).

LED plant light manufacturers will advertise the PAR levels produced by their lamps, but there are some other key indicators that accompany the PAR output, which truly separates ordinary light from high-quality LED plant lights.

Photosynthetic photon flux density (PPFD)

PPFD goes one step further. It is good to produce a large area of PAR that nourishes the plant, but if the beam spread is a wide-spreading method, then only a small part of the PAR will actually reach the leaves of the plant. The rest will overflow onto the aisles and walls, which is basically a waste of energy. PPFD measures the density of PAR that actually reaches the plant canopy.

In addition to the high PPFD value, it is important that the light is evenly distributed on the crop. Hot spots or black spots can cause overexposure or underexposure of plants to available PAR and negatively affect the overall harvest quality. This uniformity is a challenge for LED plant lights, but there are some interesting innovations in this field.

The LED plant light produced by Yaorong Technology uses precise optical elements on each diode to focus the beam on the plant and provide precise uniformity throughout the canopy, thereby making the overall harvest healthier. Make sure that the PPFD measurement value you receive from the LED lighting manufacturer is the combined average of multiple measurement points from the entire canopy.

Through the above, we know that the growth of plants is inseparable from the PAR and PPFD in the LED plant light. One can provide the plant with the wavelength and spectrum required for photosynthesis, and the other can provide the light intensity and efficiency required by the plant. The meaning of LED plant lights is to replace sunlight to fill plants with sufficient light intensity and high efficiency. At the same time, the wavelength and spectrum are customized to give plants better growth at each growth stage, so you can see why PAR and PPFD are LED plant lights The rating indicator.

What can be done to give plants better growth?

Regarding how to make plants grow better, we can start from the two points of PAR and PPFD. First, start from PAR, take plants as the object, and customize the LED plant light spectrum that can achieve better growth effects according to the needs of different plants. ,wavelength. It is best to adjust the spectrum of LED plant lights, so that the corresponding spectrum can be adjusted at each different stage, so that the plant grows best.

At this point in PPFD, we need to increase the light intensity and efficiency, and increase the light intensity. We can increase the light intensity of the plants by installing multiple lights to overlap, or adjusting the installation height. The efficiency is the same, so how do we do it?

1. Install evenly distributed

Measure the floor area. Multiply the length by the width to get the square meters of the planting area. You can make the right choice based on how much power to provide per square meter, that is, how many LED plant lights are installed per square meter. In this way, each lamp can be evenly distributed, so that the outer edge will receive strong light, so that the light will be more uniform, and the growth of plants will be more effective.

2. Illumination distance

The illumination distance of the LED plant light is very important. You have to adjust the points for different plants at different stages, and you must also unify the distance to make the illumination more uniform.

3. Adjust the light

The dimming of LED plant lights can make plants grow better at each stage, the general germination rate: 30%; seedlings: 50%-75%; growth: 75%-100%; flowering: 100%. Give plants the best growth status.

4. Efficient use of light

The LED plant lamp can also realize the efficient use of light under the condition of uniform illumination. The main physical principles used are light reflection and light refraction.

The use of light reflection and refraction not only makes the illumination more uniform, but also achieves high luminous efficiency. The reflector and the metal substrate used by the COB are mainly used. The principle of the reflector reflects the light emitted by the light source into a beam, which increases the local light intensity. The reflection effect is also to maximize the light energy emitted by the LED plant lamp beads to be used by plants, and the reflected part is auxiliary light, which also has the function of fixing the lamp beads and heat dissipation.

Using the principle of light refraction is mainly to use an optical lens. The principle changes the propagation trajectory of the light. Generally, a single lens and a retest lens are used, which can control the light distribution very accurately.

Through this article, I believe that when you choose LED plant lights in the future, you already know which standard to start from. If you want to know more, welcome to Yaorong Technology Consulting.

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